1. Field of the Invention
This invention relates to impedance “dummy” loads for light emitting diode (LED) traffic signals. More specifically, it relates to adding in-line resistive or capacitive loads to LED traffic signals to make them compatible with traffic signal controllers that were designed to work with higher power consumption incandescent light sources.
2. Description of Related Art
Existing incandecant traffic signal controllers have minimum power load requirements. When the power load is above the minimum level, the controller recognizes that there is a signal on the line. Light emitting diode (LED) traffic signals can operate at less than this threshold value. Thus, when a LED signal is retrofit into an existing signal with a controller developed for an incandecsant lamp, there must be an artificial means of creating the additional load to meet this minimum threshold value.
In prior art LED signals, a resistive load is mounted on the back of the traffic signal lamp cover and wired to the existing circuitry in such a way as to create an additive load to the existing LED array. The prior art dummy load is attached either by bolting it onto the back cover or building it into the housing.
This approach creates additional heat in the system, which can cause premature aging of the LEDs and other electronic components in the system. In addition, assembly time on the manufacturing floor is increased and more parts are required to address various load configurations. There is a need for a system which does not cause premature aging of the LEDs and/or other electrical components. Further, a system which reduces the number of parts needed is desireable.
Prior art LED signals must be manufactured with the desired dummy load matching the controller. There is a need for a system which allows a dummy load to be added, removed and/or adjusted in the field.